JP2005306535A - Rolled sheet retaining mechanism and printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To draw out sheet with constant or approximately constant driving force in the state in which load is applied to rolled sheet in order to prevent over-run regardless of a diameter and weight of the rolled sheet and to stably operate a driving part such as a motor for drawing out the sheet. <P>SOLUTION: A side surface of the rolled sheet 30 attached to a drop-in type rolled sheet holder part 15 is pressed by a press plate 92 and over-run of the rolled sheet 30 generated by inertia force is prevented. The press plate 92 is urged by two coil springs 76, 77 arranged at an inner peripheral side and an outer peripheral side of the rolled sheet 30. The coil spring 77 at the outer peripheral side has stronger elasticity than the coil spring 76 at the inner peripheral side. Thereby, pressing force of the press plate 92 by elasticity of the coil springs 76, 77 is gradually reduced accompanying with contraction of diameter of the rolled sheet 30. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a roll paper holding mechanism that rotatably holds a roll paper that rotates by pulling out an end portion of the paper, and more particularly to a roll paper holding mechanism having a structure that presses a side surface of the roll paper. The present invention also relates to a printer provided with such a roll paper holding mechanism.

  In small printers and the like, the roll paper is often used. The roll paper is rotatably held by a drop-in type that is dropped into the storage space, a shaft support type that supports a core material by a shaft, and the like, and is drawn out by a motor for printing. The roll paper rotates when the paper is pulled out for printing, but even after printing is finished, the inertial force according to the weight works, so that rotation does not stop at the same time as printing and continues to some extent. Overrun may occur. This overrun causes a sag in the outer peripheral portion of the roll paper, and the sag causes the paper to be wrinkled or broken. In view of this, there has been proposed one provided with an elastic member that always presses the side surface of the roll paper to restrict overrun (for example, Patent Document 1).

JP-A-8-217294 (summary, FIG. 1 (b), etc.)

  As described in the above publication, when the side surface of the roll paper is pressed with an elastic member, overrun can surely be prevented. In this case, since the elasticity of the elastic member is constant, the pressing force that presses the side surface of the roll paper is always constant, while the roll paper has a smaller outer diameter and weight as the roll paper is consumed. Becomes lighter. For this reason, the following malfunction may arise.

  The driving force required to pull out the roll paper to which a constant load (pressing force) is applied by the elastic member requires a larger force as the roll paper is reduced in diameter. This is because the longer the distance from the center of rotation of the roll paper to the outermost diameter from which the paper is drawn out, the less force is drawn out by the action of the moment force. For this reason, when the roll paper has a considerably small diameter, the load of the motor for pulling out the paper becomes excessive, and there is a possibility that problems such as step-out occur. Further, if a motor with a large driving force is provided to avoid such a problem, the cost increases.

  In particular, in the case of the drop-in type (as in the above publication), the roll paper is always in the bottom of the storage space due to its own weight when it is heavy at the initial stage of use. When the weight is reduced and the weight is reduced, the entire roll paper is pulled and floated by pulling out the paper, and the lifted state is held by the elastic member, and is difficult to return to the bottom of the storage space by its own weight. If the paper is pulled out in this state and printing is performed while the roll paper is rotated, the printing surface of the paper may be rubbed, or the paper may be wrinkled or folded. In addition, when a sensor is provided on the side of the roll paper to detect and notify that the paper has been reduced in order to prompt the replacement of the paper, the roll paper does not exist at a fixed position, so that the sensor malfunctions. End up.

  Therefore, the present invention can effectively prevent overrun, and can pull out the paper with a driving force that is constant or close to it regardless of the outer diameter and weight of the roll paper that varies with consumption. As a result, it is an object of the present invention to provide a roll paper holding mechanism in which a drive unit such as a paper drawing motor operates stably and does not become disadvantageous in cost, and a printer including the roll paper holding mechanism.

  The roll paper holding mechanism of the present invention includes a holding unit that rotatably holds the roll paper, a drive unit for pulling out a paper end of the roll paper held by the holding unit, and the roll paper held by the holding unit. A pressing portion that presses the side surface of the roll paper, and the pressing portion includes a pressing force adjusting means that gradually decreases the pressing force as the diameter of the roll paper is reduced. In addition, a printer of the present invention includes the roll paper holding mechanism of the present invention.

  According to the roll paper holding mechanism of the present invention, the roll paper is rotatably held by the holding unit, and the holding unit may be of the drop-in type or the shaft support type. The end portion of the roll paper held by the holding unit is pulled out by the driving unit, and the roll paper is rotated accordingly. Even when the drawing of the paper is stopped, the roll paper is restrained from being overrun due to inertia because the side surface is pressed by the pressing portion.

  In the present invention, the pressing force of the pressing portion gradually decreases as the roll paper shrinks. Such a change in the pressing force is made by the pressing force adjusting means. Roll paper is pulled out by a drive unit composed of a motor or the like. As described above, in a state where a load is applied by the pressing unit, the driving force required to pull out the paper is that of roll paper. A large force is required as the diameter is reduced.

  However, in the present invention, the load that the roll paper receives from the pressing portion is not constant as in the prior art, and gradually decreases as the roll paper shrinks. That is, in the “state where the roll paper has a large diameter → the driving force to be pulled out may be small”, the pressing force of the pressing portion is large, and in the “state in which the roll paper requires a large driving force to pull out—the pulling force” The pressure becomes smaller. Therefore, the driving force required to pull out the paper (which is comparable to the load received by the driving unit) may be constant or close to it regardless of the outer diameter and weight of the roll paper. As a result, even when the roll paper has a reduced diameter, an excessive load is not applied to the drive unit, and a stable roll paper drawing operation can be obtained. Further, it is possible to avoid the cost for the drive unit to cope with an excessive load.

  Further, when the roll paper holding unit is a drop-in type, when the roll paper is reduced in diameter and lightened, as described above, the roll paper is floated by drawing out the paper, and the state is held by the pressing unit. There are concerns about defects. However, in the present invention, since the pressing force received by the roll paper from the pressing portion gradually decreases with the diameter of the roll paper, even if the diameter is reduced and the weight is reduced, the weight of the roll paper is reduced. It is possible to overcome the pressing force and return to the bottom of the storage space. For this reason, generation | occurrence | production of the said malfunction resulting from the state with the roll paper still floating can be prevented.

The following is mentioned as a more concrete form of the roll paper holding mechanism of the present invention.
The pressing force adjusting means includes a plurality of elastic members arranged substantially in the reduced diameter direction of the roll paper and in an order in which the elasticity becomes weaker toward the reduced diameter direction.

  The pressing portion includes a pressing member that contacts the side surface of the roll paper, and the pressing force adjusting unit includes a swing mechanism that swings the pressing member gradually in one direction as the diameter of the roll paper decreases.

  The pressing unit includes a pressing member that presses a side surface of the roll paper, and the pressing force adjusting unit includes a link mechanism that biases the pressing member with a pressure corresponding to the weight of the roll paper.

  According to the present invention, the pressing force of the pressing portion that presses the side surface of the roll paper held by the holding portion is gradually reduced by the pressing force adjusting means as the roll paper is reduced in diameter. First, roll paper overrun due to inertia is effectively prevented by the pressing portion. In addition, regardless of the outer diameter and weight of the roll paper that varies with consumption, the paper can be pulled out with a driving force that is constant or close to it, and as a result, the driving unit operates stably and is applied to the driving unit. A rise in cost can be avoided.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(1) First Embodiment FIG. 1 is a small printer suitably used for an electronic cash register or the like. The printer 1 includes an outer case 10 and a cover 20 attached to the outer case 10 so as to be freely opened and closed. The outer shape is formed. 1 is a perspective view of a state in which the cover 20 is closed, and FIG. 2 is a perspective view of the state in which the cover 20 is opened. FIG. 3 is a side sectional view showing a state in which the cover 20 is closed.

  As shown in FIGS. 1 to 3, the outer case 10 has a box shape including a bottom plate 11, a pair of left and right side plates 12, a front plate 13, and a back plate 14, and a substantially semi-cylindrical shape at the rear thereof. The roll paper holder portion (holding portion) 15 is formed. The roll paper holder unit 15 is a drop-in type that drops and loads the roll paper 30 and is formed in a substantially fan shape formed on the rear side of each side plate 12 (the back side in FIGS. 1 and 2 and the right side in FIG. 3). The left and right rear plate portions 16 and the curved plate 17 connecting the arc-shaped peripheral edges of the rear plate portions 16 are formed. As shown in FIG. 3, the roll paper 30 in which the thermal paper 31 is wound around the core material 32 and accumulated in the roll paper holder 15 is drawn out with the axial direction of the core material 32 as the left-right direction. The end portion is arranged on the lower side, and the end portion is dropped and loaded so as to be pulled out forward (front side in FIGS. 1 and 2 and left side in FIG. 3).

  As shown in FIG. 3, three rollers 41, 42, and 43 whose shaft centers extend in the left-right direction are rotatably supported on the bottom of the roll paper holder unit 15. These rollers 41 to 43 are arranged along the circumferential direction of the roll paper 30 to be loaded at an appropriate interval in the front-rear direction. The roll paper 30 is placed on these rollers 41 to 43 so as to be rotatable about its axis. The roll paper 30 is rotated by the paper 31 being pulled forward, and the rollers 41 to 43 are rotated accordingly. That is, the roll paper 30 can be smoothly rotated by the rollers 41 to 43. In this case, when an unused roll paper 30 having the largest diameter (shown by a solid line in FIG. 3) is loaded, the outer peripheral surface of the roll paper 30 is placed on all the rollers 41 to 43. When the diameter is reduced with consumption, the roll paper 30 is placed on the front side and the middle rollers 41 and 42 by its own weight. Dotted lines 30A and 30B in FIG. 3 indicate roll paper with a reduced diameter.

  As shown in FIGS. 1 to 3, the cover 20 has a shape similar to the roll paper holder portion 15, is formed in a substantially semi-cylindrical shape slightly larger than the roll paper holder portion 15, and is in an open state Thus, it is incorporated so as to cover the outside of the roll paper holder 15. That is, the cover 20 includes a pair of left and right side plates 21 that are substantially fan-shaped and curved plates 22 that connect arc-shaped peripheral edges of the side plates 21, and corresponds to the axis of the curved plate 22 in each side plate 21. The portion is supported coaxially with the roll paper holder portion 15 and rotatably with respect to each rear plate portion 16 of the roll paper holder portion 15 via the cover shaft 23.

  Then, when the cover 20 is rotated to the rear side, the cover 20 expands along the outside of the roll paper holder portion 15, and as shown in FIG. 2, the opening of the outer case 10 (this opening is mainly the roll paper holder portion). 15 openings). Further, when the cover 20 is rotated forward from this state, the opening of the outer case 10 is closed as shown in FIGS. When the cover 20 is fully closed, the rear portion of the printer 1 is formed in a cylindrical shape by the roll paper holder portion 15 and the cover 20. The fully closed state of the cover 20 is detachably engaged with the outer case 10 by an engaging / disengaging means (not shown), and the fully closed state is maintained in the engaged state.

  As shown in FIG. 3, the printer 1 includes a printing mechanism 50 that performs printing on a paper 31 drawn from the roll paper 30 and a push-off type cutter mechanism 60 that cuts the printed paper 31. . The printing mechanism 50 includes a platen roller 51 attached to the tip which is the rotating end of the cover 20, and a thermal print head 52 attached to the frame 18 fixed to the front part in the exterior case 10. Is done. The print head 52 is supported by the head frame 19. The print head 52 and the head frame 19 are always urged toward the platen roller 51 by a coil spring 54 attached to a spring frame 53 fixed to the frame 18.

  When the cover 20 is closed, the platen roller 51 and the print head 52 face each other, and the print head 52 is elastically pressed against the platen roller 51 by the elasticity of the coil spring 54. The paper 31 drawn out from the roll paper 30 is sandwiched between the platen roller 51 and the print head 52 and is drawn out as the platen roller 51 rotates. Then, when the paper 31 is pulled out, the roll paper 30 rotates.

  A driven gear 55 is coaxially fixed to one end of the shaft of the platen roller 51 as shown in FIG. 2, and this driven gear 55 is incorporated into the outer case 10 when the cover 20 is fully closed. And connected to a reduction gear (both not shown) driven by a conveyance motor. When the transport motor operates in this state, the platen roller 51 is rotated in the transport direction of the paper 31 (clockwise in FIG. 3). In the following description, the upstream side and the downstream side are directions in the conveyance path of the paper 31.

  The cutter mechanism 60 is disposed immediately downstream of the printing mechanism 50 (upper side in FIG. 3), and is fixed to the fixed blade 61 fixed to the front end portion of the cover 20 and the movable fixed to the frame 18 in the exterior case 10. The blade unit 62 is configured. The movable blade unit 62 includes a movable blade 63 that is driven to reciprocate in the front-rear direction. When the cover 20 is closed, the fixed blade 61 faces the movable blade 63 with a gap through which the paper 31 passes therebetween. To do. When the movable blade 63 moves backward, the blade at the tip slides while pressing against the upper surface of the blade of the fixed blade 61, and the sheet 31 sandwiched between the blades 61 and 63 is cut by this operation.

  A pair of guide plates 46 and 47 that guide the paper 31 to the printing mechanism 50 are arranged on the upstream side of the printing mechanism 50. One guide plate 46 is provided in the exterior case 10, and the other guide plate 47 is provided at the tip of the cover 20. When the cover 20 is closed, there is a printing mechanism between the guide plates 46 and 47. A narrow paper conveyance path that leads the end of the paper 31 toward the 50 side is formed. A tension roller 44 that pushes the paper 31 upward to apply tension is disposed on the upstream side of the guide plate 46 on the exterior case 10 side. The tension roller 44 is urged upward by a leaf spring 45 provided in the exterior case 10.

  As shown in FIG. 1, one sheet of paper printed by the printing mechanism 50 and cut by the cutter mechanism 60 is sequentially applied to the outer peripheral surface of the front end portion of the cover 20 along the curved plate 22 of the cover 20. A paper stocker 24 that accumulates and accumulates is formed. The paper accumulated in the paper stocker 24 is held by a pressing plate 25. As shown in FIG. 3, a guide plate 26 that guides the paper 31 to the paper stocker 24 is formed at the distal end of the cover 20 and on the downstream side of the cutter mechanism 60.

The basic operation of the printer 1 from printing to paper cutting will be described. The operation of the printer 1 is automatically performed by, for example, a control device provided in the outer case 10.
First, in a state where the user opens the cover 20, the user pulls the end of the paper 31 from the roll paper 30 loaded in the roll paper holder 15 to the outside of the outer case 10 and closes the cover 20. When the cover 20 is closed, the paper 31 drawn from the roll paper 30 is, from the upstream side, between the guide plate 46 and the guide plate 47, between the platen roller 51 and the print head 52, the fixed blade 61 and the movable blade 63. Between the opening edge of the outer case 10 and the tip edge of the cover 20.

  Next, the cutter mechanism 60 is actuated, that is, the movable blade 63 of the movable blade unit 62 is reciprocated to cut the end portion of the paper 31, thereby entering a print standby state. The edge of the cut paper 31 is sandwiched between the opening edge of the outer case 10 and the front edge of the cover 20, but this can be pulled out and removed.

  Printing starts when a print command is supplied to the print head 52 and the transport motor. That is, printing is performed by repeating printing by the print head 52 and conveyance of the paper 31 by rotation of the platen roller 51. As the paper 31 is transported, the paper 31 is guided to the guide plate 26 and transported to the paper stocker 24.

  When printing is completed, the platen roller 51 is rotated by a predetermined length so as not to cut the print portion, and the paper 31 is conveyed. Thereafter, the cutter mechanism 60 is operated and the paper 31 is cut. The cut paper 31 is stored in the paper stocker 24.

  The roll paper holder unit 15 of the printer 1 is provided with pressing units 70 that press both side surfaces of the roll paper 30 loaded in the roll paper holder unit 15. The pressing portion 70 according to the present invention will be described in detail below.

  As shown in FIG. 2, on the inner surface of the outer case 10 ranging from the side plate 12 to the rear plate portion 16 of the roll paper holder portion 15, the inner plate is opened with a gap between the side plate 12 and the rear plate portion 16. 27 is stretched and fixed. The inner plates 27 are fixed to both side plates 12, and the rear portions of these inner plates 27 extend in the front-rear direction, and the rear ends thereof are elongated rectangular cutouts that penetrate the curved plate 17 of the roll paper holder unit 15. 71 is formed. A press plate (press member) 72 is fitted in each of the notches 71.

  The pressing plate 72 is an elongated plate material having a U-shaped cross section, and the pressing surface 72a is directed inward. As shown in FIG. 4, the front end of the pressing plate 72 is inclined so as to spread outward as it goes forward, and the rear end is bent and formed in a crank shape outward. Also, claw portions 73 and 74 are formed. The pressing plate 72 is in a state in which the front and rear end claw portions 73 and 74 are inserted into the front and rear end portions of the notch 71 from the inside and are thereby fitted into the notch 71. In addition, a spring seat plate 75 is disposed outside the notch 71 with a predetermined space between the notch 71 and the pressing plate 72.

  The spring seat plate 75 is stretched across the end edges of the inner plate 27 and the curved plate 17 and fixed. The pressing plate 72 is movable in the lateral direction (vertical direction in FIG. 4), but includes two front and rear coil springs (elastic members) sandwiched and mounted between the pressing plate 72 itself and the spring seat plate 75. ) Is always urged inward by 76 and 77, and the front and rear claw portions 73 and 74 are engaged with the outer surface of the inner plate 27 and the edge of the curved plate 17, respectively, thereby fitting into the notch 71. State is maintained.

  As shown in FIG. 4, the outer surface of the inner plate 27 with which the front claw portion 73 engages is located slightly inside the edge of the curved plate 17 with which the rear claw portion 74 engages. For this reason, as shown in FIG. 4 (a), when the roll paper holder 15 is empty, the pressing surface 72a of the pressing plate 72 facing inward is inclined so as to gradually protrude toward the front. In addition, the entire pressing surface 72 a slightly protrudes inward from the inner surface of the inner plate 27 so as to be able to contact the side surface of the roll paper 30.

  As shown in FIG. 3, the pressing plate 72 has a substantially horizontal radial direction from the outer peripheral edge of the roll paper 30 toward the core member 32 with respect to the maximum outer diameter roll paper 30 loaded in the roll paper holder unit 15. The length of the roll paper 30 is longer than half of the radius of the roll paper 30, for example, about 3/4 of the radius. When the roll paper 30 is loaded into the roll paper holder unit 15, the pressing plate 72 is pushed by the side surface of the roll paper 30 and slightly moves outward, so that both side surfaces of the roll paper 30 are 2 The pressing surface 72a of the pressing plate 72 urged inward by the urging force of the two coil springs 76 and 77 is pressed against each other.

  Here, the elasticity of the two coil springs 76 and 77 arranged at an appropriate interval in the front and back is different, and the coil spring 77 on the rear side (the outer peripheral side of the roll paper 30) is more on the front side (roll paper). The one having higher elasticity than the coil spring 76 on the inner peripheral side of 30 is used. As shown in FIG. 4B, these two coil springs 76 and 77 are both on the side surface of the roll paper 30 when the roll paper 30 has the maximum diameter (indicated by the solid line 30 in FIG. 3). Opposing across the pressing plate 72. In this state, the side surface of the roll paper 30 is mainly pressed by the pressing plate 72 that receives the force of the highly elastic coil spring 77 on the outer peripheral side. Note that the alternate long and short dash line in FIG.

  Next, as shown in FIG. 4C, when the diameter of the roll paper 30 is reduced to about half due to consumption of the paper 31 (in a state indicated by 30 </ b> A in FIG. 3), the coil spring 77 on the outer peripheral side becomes Deviate from the sides. In this state, the influence of the pressing force by the coil spring 77 on the outer peripheral side is reduced, and instead, the influence of the pressing force by the coil spring 76 on the inner peripheral side having weak elasticity is increased. That is, the side surface of the roll paper 30 is pressed by the pressing plate 72 with a pressing force weaker than that when the roll paper 30 has the maximum diameter. When the consumption of the paper 31 further progresses and the roll paper 30 has a small diameter as shown in FIG. 4D (in the state shown by 30B in FIG. 3), the coil spring 76 on the inner peripheral side also moves from the side of the roll paper 30. Come off. In this state, only the pressing force of the inner peripheral side coil spring 76 is applied to the side surface of the roll paper 30.

  As can be seen from the above operation, according to the pressing unit 70, the pressing force that presses the side surface of the roll paper 30 with the pressing plate 72 gradually decreases as the diameter of the roll paper 30 decreases. According to the pressing unit 70, first, the side surface of the roll paper 30 is pressed by the pressing plate 72, whereby an overrun in which the roll paper 30 continues to rotate due to the inertial force generated in the roll paper 30 when printing is stopped. Be regulated. For this reason, sagging of the paper 31 due to overrun, and wrinkling and folding of the paper 31 due to the sagging are prevented.

  Further, even if the roll paper 30 is reduced in diameter and lightened, the pressing force from the pressing portion 70 received by the side surface of the roll paper 30 gradually decreases as the roll paper 30 is reduced in diameter. The dead weight can overcome the pressing force of the pressing portion 70 and return to the bottom of the roll paper holder portion 15. For this reason, problems such as rubbing of the printing surface and wrinkling or folding of the paper 31 caused by printing with the roll paper 30 still floating do not occur. In addition, when a sensor for detecting and notifying that the paper 31 has been reduced in order to prompt the replacement of the paper 31 is provided, the roll paper 30 is always present at a fixed position of the roll paper holder unit 15. The sensor works reliably.

  In addition, the paper 31 is pulled out from the roll paper 30 by the rotating action of the platen roller 51 that is rotated by the transport motor. However, in the roll paper 30 in which a load is applied to the side surface in order to prevent overrun, the paper 31 is changed. The driving force required for pulling out requires a large force as the roll paper 30 is reduced in diameter. However, in this embodiment, the load received by the roll paper 30 from the pressing unit 70 is not constant, and in the “state in which the roll paper 30 has a large diameter → the driving force to be pulled out may be small”, the pressing force of the pressing unit 70 is large, In the “state in which the roll paper 30 requires a large driving force for pulling out a small diameter → drawing”, the pressing force of the pressing unit 70 is small.

  Therefore, it can be said that the driving force by the transport motor necessary for pulling out the paper 31 may be constant or close to it regardless of the outer diameter and weight of the roll paper 30. As a result, even when the diameter of the roll paper 30 is reduced, an excessive load is not applied to the drive unit including the conveyance motor and the reduction gear, and a stable operation of pulling out the roll paper 30 can be obtained. Further, it is possible to avoid the cost for the drive unit to cope with an excessive load.

(2) 2nd Embodiment Next, with reference to FIG. 5, the press part 80 of 2nd Embodiment which is another form of the press part 70 of the said 1st Embodiment is demonstrated.
Reference numeral 82 in FIG. 5 denotes a pressing plate (pressing member) constituting the pressing portion 80 of the second embodiment, and this pressing plate 82 is substantially the same as the pressing plate 72 of the first embodiment, but the front end. The claw portion 73 is not formed, and the front end portion and the rear end claw portion 74 are not inserted into the notch 71 of the inner plate 27. Furthermore, in this embodiment, a rectangular leaf spring 83 extending in the front-rear direction is provided as an alternative to the spring seat plate 75 and the two coil springs 76 and 77 of the first embodiment.

  In the leaf spring 83, the front end portion which is one end portion in the longitudinal direction is supported by one side on the outer surface of the front portion with respect to the notch 71 in the inner plate 27, and in FIG. Elastically deforms in the direction of arrows A-B. The pressing plate 82 is swingably attached to a slightly rear portion of the middle portion in the longitudinal direction of the leaf spring 83 via a shaft 84 extending in the vertical direction. In this case, the shaft 84 and the leaf spring 83 constitute a swing mechanism according to the present invention. The leaf spring 83 is straight and free when the roll paper holder 15 is empty as shown in FIG. 5A. At this time, the entire pressing surface 82a of the pressing plate 82 is placed on the side surface of the roll paper 30. It protrudes slightly inward so that it can abut.

  According to the pressing unit 80 of the second embodiment, as shown in FIG. 5B, when the roll paper 30 loaded in the roll paper holder unit 15 has the maximum diameter, the pressing plate 82 is provided on the side surface of the roll paper 30. When pressed, the leaf spring 83 warps outward, the pressing plate 82 swings about the shaft 84 as a fulcrum, and the entire pressing surface 82 a is in close contact with the side surface of the roll paper 30. The side surface of the roll paper 30 is pressed by the pressing plate 82 that receives the elasticity of the leaf spring 83. At this time, the shaft (the shaft support portion of the pressing plate 82) 84 faces the side surface of the roll paper 30 with the pressing plate 82 interposed therebetween, and therefore the leaf spring 83 is maximally warped in this case. become.

  Next, as shown in FIG. 5C, when the diameter of the roll paper 30 is reduced to about half due to consumption of the paper 31, the shaft support part is detached from the side surface of the roll paper 30, and the elasticity of the leaf spring 83 The pressing plate 82 swings in the direction of arrow C with the shaft 84 as a fulcrum, and the shaft 84 moves inward. The roll paper 30 receives a pressing force from the pressing plate 82 at the outer peripheral edge and the side surface in the vicinity thereof. At this time, the warp angle of the leaf spring 83 becomes smaller than that in FIG. 5B, and the elasticity also decreases. The warp angle of the leaf spring 83 decreases as the contact position of the outer peripheral edge of the roll paper 30 with respect to the pressing plate 82 becomes forward, and the elasticity gradually decreases accordingly. When the consumption of the paper 31 further progresses and the roll paper 30 becomes smaller in diameter as shown in FIG. 5D, the pressing plate 82 is gradually swung in the C direction, and the front end abuts near the base of the leaf spring 83. . At this time, the leaf spring 83 is in a free state, and the roll paper 30 receives almost no pressing force from the pressing plate 82.

  As described above, according to the pressing unit 80 of the second embodiment, the elasticity of the leaf spring 83 gradually decreases as the diameter of the roll paper 30 decreases, and accordingly, the pressing of pressing the side surface of the roll paper 30 with the pressing plate 82. The pressure decreases as well. For this reason, as in the first embodiment, it is possible to prevent overrun of the roll paper 30 and, of course, even if the diameter is reduced and the weight is reduced, the roll paper 30 does not remain floating and returns to a fixed position by its own weight. In addition, various effects can be obtained by the action such as that the paper 31 can be pulled out with a constant driving force.

(3) Third Embodiment FIGS. 6 and 7 are diagrams schematically illustrating a third embodiment in which the side surface of the roll paper 30 is pressed using its own weight. The roll paper holder part (holding part) 90 in this case is a drop-in type, and is constituted by a pair of left and right pressing plates (pressing members) 92. These pressing plates 92 have a rectangular shape longer than the diameter of the roll paper 30 having the largest diameter, and when the roll paper 30 is loaded, the press plates 92 extend in the vertical direction and face the roll paper 30 in parallel with each other. Built to be able to.

  A bearing 92a is formed on the outer surface of one end (the lower end in FIGS. 6 and 7) of each pressing plate 92, and a support shaft 93 extending horizontally is passed through the bearing 92a. These support shafts 93 are fixed in parallel to each other on a frame or the like of a printer (not shown), whereby each pressing plate 92 is rotated in the direction of arrow DE in FIG. It is supposed to be free. A pair of front and rear rollers 94 is rotatably supported via a roller shaft 94a that is horizontal and orthogonal to the support shaft 93 on the inner side of each pressing plate 92 further on the lower end side than the bearing 92a. In this case, the pressing plate 92, the support shaft 93, and the roller 94 constitute a link mechanism according to the present invention.

  In this roll paper holding mechanism, the roll paper 30 is placed on the left and right rollers 94. Then, each pressing plate 92 rotates in the direction of arrow D in FIG. 7A with the support shaft 93 as a fulcrum, the inner surface is in close contact with the side surface of the roll paper 30, and the roll is rotated with a force corresponding to the weight of the roll paper 30. The side surface of the paper 30 is pressed by the pressing plate 92. As the roll paper 30 is drawn out and consumed, the diameter of the roll paper 30 is reduced and the weight is reduced as shown in FIG. The pressing force is also reduced by reducing the area of the side surface of the roll paper 30 that is in close contact with the inner surface of the pressing plate 92 and reducing the friction.

(4) Fourth Embodiment FIGS. 8 and 9 are diagrams schematically showing a roll paper holding mechanism that presses the side surface of the roll paper 30 using its own weight as in the third embodiment. . The roll paper holder unit (holding unit) 100 of this embodiment is a pivotal support type, and the roll paper 30 is rotatably supported by a pair of left and right rollers 101 inserted into the core member 32. The roller 101 is rotatably supported by a pair of left and right pressing plates (pressing members) 102. The pressing plate 102 is the same as the pressing plate 92 of the third embodiment, and has a bearing 102a at the lower end, and through a support shaft 103 that passes through the bearing 102a and is fixed to a frame (not shown). It is rotatable in the direction of arrow FG shown in FIG. The roller 101 is rotatably supported at a central portion in the width direction on the inner side of the lower end side of the bearing 102 a of the pressing plate 102 via a roller shaft 101 a that is horizontal and orthogonal to the support shaft 103. Note that one of the frames (not shown) that fixes the support shaft 103 can be moved and fixed in the left-right direction in FIG. 9. When setting the roll paper 30, the roll paper 30 is set after the frame is moved outward, and then the frame is moved inward and fixed. In this case, the pressing plate 102, the support shaft 103, and the roller 101 constitute a link mechanism according to the present invention.

  In this roll paper holding mechanism, the roll paper 30 is rotatably supported in a state where the left and right rollers 101 are inserted into the core member 32 and are hung from these rollers 101. In this state, the left and right pressing plates 102 rotate in the direction of arrow F in FIG. 9A with the support shaft 103 as a fulcrum, the inner surface is in close contact with the side surface of the roll paper 30, and the force corresponding to the weight of the roll paper 30 Thus, the side surface of the roll paper 30 is pressed by the pressing plate 102. In this case, the pressing plate 92 is slightly longer than the radius of the roll paper 30 having the maximum diameter, and presses the portion above the core material 23 of the roll paper 30. As the paper is drawn out and consumed, the roll paper 30 is reduced in diameter and reduced in weight as shown in FIG. 9B, but is received from the pressing plate 102 as the diameter is reduced. The pressing force also decreases.

  In the roll paper holding mechanism of the third and fourth embodiments, the side surface of the roll paper 30 is pressed by the press plates 92 and 102 due to its own weight, and the roll paper 30 is consumed and the diameter thereof is reduced. The pressing force by 92 and 102 gradually decreases. Accordingly, in these embodiments as well as in the first and second embodiments, effects such as prevention of overrun of the roll paper 30 and drawing of the paper with a constant driving force can be obtained, and drop-in can be achieved. In the third embodiment of the equation, problems that occur when the roll paper 30 remains floating are prevented.

1 is a perspective view of a printer according to a first embodiment of the present invention in a cover closed state. It is a perspective view of the cover open state of the printer concerning a 1st embodiment. It is side surface sectional drawing of the cover closed state of the printer which concerns on 1st Embodiment. (A)-(d) is a plane sectional view showing composition and an operation of a press part concerning a 1st embodiment. (A)-(d) is a plane sectional view showing composition and an operation of a press part concerning a 2nd embodiment of the present invention. It is a side view of the roll paper holding mechanism which concerns on 3rd Embodiment of this invention. It is front sectional drawing of the roll paper holding | maintenance mechanism which concerns on 3rd Embodiment, Comprising: (a) has shown the state whose roll paper is the maximum diameter, (b) has shown the state where roll paper is a small diameter. It is a side view of the roll paper holding mechanism which concerns on 4th Embodiment of this invention. It is front sectional drawing of the roll paper holding mechanism which concerns on 4th Embodiment, Comprising: (a) has shown the state whose roll paper is the maximum diameter, (b) has shown the state where roll paper has a small diameter.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Printer 15, 90, 100 ... Roll paper holder part (holding part)
30 ... Roll paper 70, 80 ... Pressing part 72, 82, 92, 102 ... Pressing plate (pressing member)
76, 77 ... Coil spring (elastic member, pressing force adjusting means)

Claims (5)

A holding unit for holding the roll paper rotatably;
A drive unit for pulling out the end of the roll paper held by the holding unit;
A pressing unit that presses a side surface of the roll paper held by the holding unit,
The roll paper holding mechanism, wherein the pressing unit includes a pressing force adjusting unit that gradually decreases the pressing force as the diameter of the roll paper decreases.   The pressing force adjusting means includes a plurality of elastic members arranged substantially in the reduced diameter direction of the roll paper and in an order in which the elasticity becomes weaker toward the reduced diameter direction. Item 2. A roll paper holding mechanism according to Item 1. The pressing portion includes a pressing member that contacts a side surface of the roll paper,
2. The roll paper holding mechanism according to claim 1, wherein the pressing force adjusting unit includes a swinging mechanism that swings the pressing member gradually in one direction as the diameter of the roll paper decreases. The pressing portion includes a pressing member that presses a side surface of the roll paper,
The roll paper holding mechanism according to claim 1, wherein the pressing force adjusting unit includes a link mechanism that urges the pressing member with a pressure corresponding to the weight of the roll paper. A printer comprising the roll paper holding mechanism according to claim 1.

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